If you are new to chess, the sequences that good players use to win games may seem impossibly complicated. But most of them actually are based on just a few general concepts combined ingeniously and persistently. This frame and the ones that follow explain the concepts broadly. The rest of the site teaches their use in detail.

The most important idea in chess is the double threat. Generally speaking a double threat is any move you make that presents your opponent with two problems at the same time. Since each player can make just one move per turn, your opponent only has time to address one of the threats you have made. On your next turn you execute the other one. Maybe your first move checks his king and attacks another of his pieces at the same time; or maybe you threaten one of his pieces and are building a threat of checkmate elsewhere. The result is the same: your opponent has to spend his next move dealing with your threat against his king, and then you get to take the other piece you were threatening.

The universe of chess tactics can be divided into four or five great families of ideas, each of them a variation on the logic of the double threat. This site is organized around them:

1. The first family, and the best-known type of double threat, is the fork—a move where one of your pieces attacks two enemy pieces at the same time. You no doubt have seen examples of knight forks if you have played chess for a while; the knight naturally lends itself to moves in which it attacks two pieces at once. But the same idea can be executed with your queen or with other pieces, as we shall see.

2. A second type of double threat, and another family of tactical ideas, is the discovered attack. This occurs when you move one of your pieces out of the way of another so that both of them make separate attacks against your opponent. Again, he only has time to parry one of the threats. You play out the other one on your next move.

3. A third family of tactical ideas involves the pin or skewer. These occur when two of your opponent’s pieces are on the same line and you place an attacker so that it runs through both of them. In effect you again are making a double threat—one threat against the piece in front and another against the piece behind it.

4. And then there are countless other situations that may be lumped under the heading of removing the guard, in which you capture or harry an enemy piece that guards something else you want to take. Your opponent can’t defend against both threats on the one turn allowed to him, so you are able to play one of them or the other.

In effect most games of chess are contests to see who can find a way to use one of those tactical techniques first. One successful fork (or discovery, or skewer, etc.) often decides a game by giving one player an insurmountable advantage over the other. This is why Richard Teichmann said that chess is 99% tactics; and it is why mastery of tactics is the key to having fun at the chessboard, not to mention winning.

[Note: A fifth family of tactical operations involves mating patterns: characteristic ways that kings get trapped. These are treated in the last section of this site. They do not necessarily involve the logic of the double threat in the way that those tactical devices just described do. We also are leaving aside a few other, more minor families of tactics for now.]